I'd only go with the ability to go to one of these alternate realities. Flonyard seems nice.

But if I had to pick four more.

Shana's coat with its armour propities as well as being an extra dimentional pocket.

The ability to talk to animals.

suitable skills for the alternate dimention, be it magic, sword play or somthing more mundane. It would help fit in after all

The obligatory loli sidekick/ side charicter, not for romantic or dubious reason but more because the tend to be awesome. Fate/stay's Illya made a good example for comidy and badassery when she wasn't busy creeping into shiro's bed.

Failing the alternate world, I guess I could live with Nervegear instead

1. Ichigo's bankai suit (Bleach). Seriously, that is one bad (shut your mouth) outfit.
2. Izayoi powers (guy from Problem children are coming from another world, aren't they?). Who wouldn't want powers that are so freaking powerful that they're an "unknown" ability?
3. Mobile suit. Orbital Frame (Z.O.E.), Gundam, Knightframe (Code Geass), Macross mech, don't care which one, I want one.
4. Animal girl as a friend/sidekick (Aisha, Outlaw Star; Eris, Cat Planet Cuties; Ku-chan, Fox Deity; Kanokon). I don't know why but I find animal girls interesting, especially their behavior towards humans or other creatures.
5. Instant transmission/alchemy. I'm kindof torn between the two because both are cool to have, but I think I would be happy with one or the other.

The Black Reapers Coat from Darker than Black.
The Parasol machine gun that Kagura uses in Gintama.
The ability to do that awesome hypnosis thing that guy from Angel Beats does. (I forget his name.)
Have a Cyborg body like in Ghost in the Shell.
And my own wisecracking imaginary sidekick like in Afro Samurai.

1. Lucy Heartfilia (Fairy Tail) <3
2. Garlic Jr's Immortality (DBZ) Who wouldn't want to live forever?
3. Sasuke's Sharingan (Naruto) Deus Ex Machina is always useful
4. Shirou's Unlimited Blade Works (Fate/Stay Night) Badass attack that would let me use any weapon I have ever come across, how awesome is that?
5. Touma's Imagine Breaker (Index/Railgun) So no other powers could ever be used against me.. Shit, but I just cancelled all of my powers too.. Well at least I still have Lucy!